1. Technical Field
The present invention relates generally to an optical disc player for reproducing signals recorded on an optical disc and, more particularly, to a digital signal processing apparatus and method for reproducing digital signals read from an optical disc regardless of the type of disc and providing a mechanism for controlling the output of the reproduced digital signals.
2. Description of the Related Art
A compact disc (CD), which is a type of optical disc, is a storage medium that can store a large amount of information. An audio disc stores stereo audio signals that are generated from two 16-bit data words sampled at 44.1 MHz. Audio data is typically output from an audio disc player at the rate of 1.41xc3x97106 bits/sec. Data for error-correction, synchronization and modulation are also necessary for reproducing signals recorded on an optical disc. A channel bit rate, which is the rate at which data is read from a disc, is typically 4.3218 Mbps. Different types of CDs include CD-audio (or CD-DA) on which audio data is recorded, CD-ROM on which data or a video signals are stored, CD-I on which multimedia information are interactively recorded, and video CD.
An optical disc player for reproducing information stored on the above optical discs typically comprises a plurality of hardware components including, for example, an analog signal processing unit, a servo unit, a digital signal processing unit, and an output unit. An analog signal extracted from the optical disc is amplified and processed by the analog signal processing unit to remove noise. Further, demodulation, de-interleaving and error-correction are performed on the analog signal in the digital signal processing unit. The audio data is then transmitted to the output unit for playback to the user. More specifically, the output unit decodes the CD-ROM and converts a digital signal to an analog signal. The servo unit controls the position on the optical disc from which signals are extracted.
In conventional systems, the data output from the digital signal processing unit is serially transmitted to the output unit. With respect to such serial data transmission, the digital signal processing unit is the master and the output unit is the slave. As such, the audio data is unilaterally transmitted to the output unit. One problem associated with this configuration is the lack of a mechanism for controlling the memory of the output unit, which results in a high probability that an error will occur. Thus, a system and method that would reduce such data error is highly desirable.
The present invention is directed to an apparatus and method for controlling the output of digitally processed data in an optical disc player so as to reduce the probability of error and lost data during such output.
In one aspect of the invention, an apparatus for processing information on an optical disc comprises a signal processor for processing a digital signal corresponding to an analog signal read from the optical disc to generate output data, a memory unit, operatively associated with the signal processor, for temporarily storing the output data in predetermined units under the control of the signal processor, and an output unit, operatively connected to the signal processor, for processing the output data based on the type of optical disc. The output unit generates a request signal that causes the signal processor to retrieve output data from the memory unit and transmit the retrieved output data to the output unit in parallel. The signal processor activates an acknowledge signal such that output data transmitted to the output unit while the acknowledge signal is activated is deemed valid by the output unit.
In another aspect, the output data comprises demodulated data and corresponding error-corrected data, and the memory unit preferably comprises a first memory region for storing the demodulated data, a second memory region for storing the error-corrected data, and a third memory region for receiving the error-corrected data and storing the data in predetermined blocks. The data stored in the third memory region comprises the output data that is transmitted in parallel by the signal processor to the output unit.
In yet another aspect of the invention, an apparatus for processing information on an optical disc comprises a first signal processor for receiving a digital signal generated from an analog signal read from the optical disc, performing demodulation and error-correction with respect to the received digital signal to generate main data and corresponding subcode data for output, a memory unit for temporarily storing the main data and corresponding subcode data in predetermined units, a second signal processor for reading the main data and corresponding subcode data from the memory unit and outputting the main data and corresponding subcode data in parallel together with an acknowledge signal, in response to a predetermined request signal, and an output unit for outputting the request signal to the second signal processor and receiving in response thereto the main data and corresponding subcode data in parallel and the acknowledgment signal so as to process the main data based on the subcode data.
Preferably, the memory unit comprises a first memory region for storing demodulated data, a second memory region for storing error-corrected demodulated data, and a third memory region for temporarily storing the error-corrected demodulated data in predetermined units. The error-corrected demodulated data stored in the third memory region comprises the main data and corresponding subcode data that are output in parallel by the second signal processor.
In another aspect of the present invention, an optical disc player comprises an analog signal processor for processing an analog signal extracted from an optical disc to generate preliminary signal processed data, a digital signal processor for processing the preliminary signal processed data to generate digital signal processed data, storing the digital signal processed data in memory, retrieving the digital signal processed data from memory in response to a request signal, generating an acknowledge signal, and outputting the digital signal processed data in parallel together with the acknowledge signal, and an output unit for outputting the request signal to the digital signal processor, receiving the digital signal processed data in parallel, decoding the digital signal processed data based on the type of optical disc and outputting the decoded data to terminal equipment.
Preferably, the digital signal processor comprises a first memory region for storing demodulated data generated by the digital signal processor from demodulating the preliminary signal processed data, a second memory region for storing error-corrected data generated by the digital signal processor from error-correcting the demodulated data and a third memory region for receiving the error-corrected data and storing the data in predetermined block units. The data stored in the third memory region comprises the digital signal processed data that is output in parallel to the output unit.
In yet another aspect of the invention, a method for processing information on an optical disc comprises the steps of processing an analog signal extracted from an optical disc to generate preliminary signal processed data, digital signal processing the preliminary signal processed data to generate digital signal processed data, generating a first control signal to output the digital signal processed data, and generating a second control signal and outputting the digital signal processed data in parallel together with the second control signal, in response to the first control signal. Digital signal processed data that is output during a period in which the second control signal is not activated is deemed invalid output data.